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Effect of the Temperature and Solvents on the Solvolysis of Barium Bromide in Aqueous-Organic Solutions: Volumetric and Viscometric Study

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Effect of the Temperature and Solvents on the Solvolysis of Barium Bromide in Aqueous-Organic Solutions: Volumetric and Viscometric Study Article Volume 12, Issue 1, 2022, 339 - 350 https://doi.org/10.33263/BRIAC121.339350 Effect of the Temperature and Solvents on the Solvolysis of Barium Bromide in Aqueous-Organic Solutions: Volumetric and Viscometric Study Sudhansu Sekhar Pattnaik 1 , Binita Nanda 2 , Biswajit Dalai 1 , Braja B. Nanda 3, * 1 Department of Physics, GIET University, Gunupur, Odisha, India; [email protected] (S.S.P.); 2 Department of Chemistry, ITER, Sikshya ‘O’ Anusandhan (Deemed to be University), Bhubaneswar-751030, India; [email protected] (B.N.); 3 P.G. Department of Chemistry, Vikram Deb Autonomous College, Jeypore-764001, Odisha, India; [email protected] (B.B.N.); * Correspondence: [email protected]; Scopus Author ID 8431581400 Received: 23.02.2021; Revised: 2.04.2021; Accepted: 7.04.2021; Published: 20.04.2021 Abstract: Volumetric and viscometric properties of solutions containing barium bromide in an aqueous solution of ethylene glycol and 1,4-dioxane have been discussed at different temperatures such as 298.15K 303.15K, 308.15K, and 313.15K. The Masson’s equation was used to determine the apparent 0 0 molar volume, 푉휙, standard partial molar volume, 푉휙 , molar expansibilities,퐸휙 by taking the density data. The values of viscosity and density were used in the Jones-Dole equation to find the viscosity B coefficients, which were used to estimate the ion-solvent interactions. The values of Hepler’s constant 2 0 2 (휕 푉휙 / 휕T )p and the viscosity B-coefficients have been used to deduce the solvent structure-promoting or structure breaking tendency of the salt in the studied mixtures. In the current study, the positive values of Hepler’s constant and the negative values of dB/dT show that barium bromide in the considered solvents mainly behaves as a structure promoter. Keywords: Apparent molar volume; Hepler’s constant; barium bromide; Jones–Dole equation. © 2021 by the authors. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). 1. Introduction Partial molar volume and viscosity data provide valuable evidence about different types of forces of attractions present in the solutions [1-5]. The volumetric and viscometric studies of solutions help us illustrate solutes' organization and properties in mixed solvents [6-10]. Recently, many researchers have studied the solution properties of the different salts in mixed solutions [11-16]. Frank and Evan [17] have interpreted the thermodynamic properties of the aqueous-organic solutions in terms of water particles' organization about the non-polar solute. 1, 4-Dioxane is a heterocyclic colorless organic liquid having a faint sweet smell like to diether. It is used as a (i) versatile aprotic solvent for cellulose esters, inks, and adhesives, (ii) as a stabilizer for transporting chlorinated hydrocarbons in aluminum vessels. Due to its lower toxicity and higher boiling point, it substituted Tetrahydrofuran in some reactions and was used as an internal standard for NMR spectroscopy of deuterium oxide. It serves as a chelating diether ligand and can solvate many inorganic compounds due to the presence of two oxygen atoms in it. Similarly, ethylene glycol is used in many commercial and industrial applications, including antifreeze and coolant. The salt, barium bromide, BaBr2 have many applications in https://biointerfaceresearch.com/ 339 https://doi.org/10.33263/BRIAC121.339350 the field of chemical reactions. It is used as a precursor to chemicals used in photography and used to purify radium in the fractional crystallization process. This paper is dealt with the study of the ion-solvent, ion-ion, and solvent-solvent interactions of the barium bromide with the aqueous solutions of dioxane and ethylene glycol, as both the solute and the solvents are used for industrial processes. Therefore, the volumetric and viscometric properties of BaBr2 in aqueous-organic solvents such as 1, 4-dioxane, and ethylene glycol, have been studied to evaluate the ion-solvent and ion-ion interactions existing among the solutes and solvents. 2. Materials and Methods 2.1. Chemicals. Anhydrous barium bromide, ethylene glycol, and 1,4-dioxane used were taken from Sigma Aldrich, Germany, with more than 99% purity and then refined by standard methods [18]. The triply distilled water was used to prepare the solutions of 10, 20, and 30(v/v) % of each of ethylene glycol and dioxane solutions, which served as solvents. Barium bromide was further desiccated over anhydrous CaCl2 before use [19]. The sample specification is given in Table 1. Table 1. Specification of Chemicals. Chemicals Source Mass fraction Purification CAS No Mol.Mass/ Structure puritya method g mol-1 Barium bromide Sigma- 0.99 Used as 10553-31-8 297.14 BaBr2 Aldrich obtained Ethylene Glycol Sigma- >0.998 By standard 107-21-1 62.07 Aldrich methods[18] 1,4-Dioxane Sigma- >0.99 By standard 123-91-1 88.11 Aldrich methods[18] aAs declared by the supplier 2.2. Apparatus and procedure. The masses of the solute and solvents were measured by electronic balance (KERN, model ABJ-220-4NM, made in Germany) with a precision of ± 0.01mg. A double arm pycnometer was taken to determine the density (ρ) of the prepared solutions at T=(298.15- 313.15) K, which was calibrated with deionized triply distilled water with 997.017 kg/m3 as its density at temperature 298.15 K. The measurement of viscosity of the solutions was done with the help of Ostwald viscometer with appropriately long reflux period greater than 200 seconds to avoid the corrections in kinetic energy. The average of three readings from the Ostwald viscometer was taken into consideration. The density bottle and viscometer were calibrated [20-21] using distilled water. All the measurements are carried out by clamping pyknometer and viscometer in a water bath maintained at constant temperatures ±0.01 K. The uncertainty in viscosity and density measurements were within ±0.003 mPa and 1 ×10-5 g cm-3 respectively. The water's viscosity was taken to be 0.7194×10-3 kg m-1 s-1 (at 303.15K) [22]. The molar concentrations of the solutions were converted to molality using the standard formula using the density values. https://biointerfaceresearch.com/ 340 https://doi.org/10.33263/BRIAC121.339350 3. Results and Discussion 3.1. Viscometric study: The properties of electrolytic solutions in aqueous media are highly particular to the individual ions of the respective electrolyte, so it is difficult to generalize these properties. Another parameter to find the ion solvent interactions is the determination of transport property in terms of viscosity. The formula: η/ηo= (t × ρ)/ (t0 × ρ0) was used to calculate the relative viscosity of the solutions, where η is the absolute viscosity, t is the time of flow and ρ is the density of solution respectively, while η0, t0, and ρ0 are the same measure for the solvent respectively. The densities of solutions are tabulated in Table 2. The dependence of viscosities of BaBr2 solutions in aqueous dioxane and ethylene glycol with the molality can be expressed by the Jones-Dole equation [23] as given below: 휂푟= η /ηo = 1+A √푚퐴+ B푚퐴 (1) Where 휂푟 is the relative viscosity of the studied solutions, η and ηo are the viscosities of solutions and solvent, respectively. The constant A represents the interionic forces [24-25], and known as the Falkenhagen coefficient, the coefficient B is associated with the solute-solvent interactions and is understood as a degree of the structure-promoting or structure breaking nature of the ions in the said solutions [26]. The parameters A and B can be found by arranging equation 1 as follows: (η/ηo ‒1) / √푚퐴 = sp/√푚퐴 = A + B √푚퐴 (2) (η/ηo ‒1) is known as specific viscosity and represented as sp. The values of (η/ηo ‒1)/ √푚퐴 and the parameters A and B coefficients of the above equation are tabulated in Tables 3 and 4, respectively. The variation of (η/ηo ‒1)/ √푚퐴 with molality ‘√푚퐴 ’ indicates the decrease of viscosity with the increase in temperature and viscosity increase with an increase of dioxane/ethylene glycol content in the solutions. The variation of viscosity with the molal concentration of solutions at 298.15 K is given in Figure 1. (a) (b) 1/2 1/2 Figure 1. The plot (휂⁄휂0 − 1)/mA vs. mA of BaBr2 in (a) DO -Water and (b) EG -Water respectively at 298.15K. The intermolecular force of attraction increases with an increase in the mass fraction of BaBr2 in the solution; as a result, the viscosity of the solution increases. The positive values of https://biointerfaceresearch.com/ 341 https://doi.org/10.33263/BRIAC121.339350 coefficient A at all temperatures for BaBr2 prove the existence of substantial ion-ion interactions. The viscosity B coefficient of the Jones-Dole equation indicates the presence of ion-solvent interaction [22]. For all the solutions, the values of viscosity B coefficients may be positive or negative. If the solute attracts the water/solvent molecules, then its B coefficient value will be positive; otherwise, it will be negative. In the present study, the positive values of viscosity B coefficient for BaBr2 in both dioxane-water and ethylene glycol-water media (Table 4) confirms the existence of ion-solvent interactions. The negative values of thermal coefficient (dB/dT) [25] indicate that there are strong ion-solvent interactions and the said solute is a structure promoter in the studied media. These data agree with the result obtained from the Hepler equation discussed in volumetric properties [27]. Table 2. Density, ρ, and apparent molar volume, 푉휙 of Barium bromide in ethylene glycol-water and 1,4- dioxane-water respectively at T= (298.15 – 313.15)K.
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